This project will investigate somesthetic sensitivity in the oral cavity of humans. Using threshold and suprathreshold psychophysical techniques, the research will (1) explore the sensitivity of the oral cavity to thermal and mechanical stimulation, (2) evaluate current theories of somatosensory physiology in light of the psychophysical data collected on mucocutaneous skin, and (3) provide germinal data on the role somethesis plays in the ingestion process. Research will focus first on oral thermal sensitivity, about which little is known. Later work will address the possible existence on mucocutaneous skin of interactions between the thermal and tactile senses that are known to occur on glabrous and hairy skin. Interactions that will come under study include the modulation of tactile sensations of pressure, vibration and texture caused by cooling or warming the skin, the enhancement of tactile sensations caused by cooling or warming the mechanical stimulus, and the referral of thermal sensations to the location of nearby tactile stimulation. The presence or absence of these phenomena will be interpreted both in terms of the neural systems that may underlie them, and the consequences they could have for the integrated function of the somesthetic and chemical senses during ingestion